Would a "gay gene" mean the end of gays?

I had a conversation with an atheist friend of mine the other night. He firmly believes that being gay is genetic and is a gene that is passed on from family.

His theory is this. He believes that for generations when homosexuality was not accepted, gays married out of social pressure and had children. Thus the gay gene was passed on. Now that the social pressure is no longer there and very few gays are opting to have natural children if they have children at all, then he believes that gays will diminish and finally be eliminated from the gene pool. He figures in 50 years there will be very few gays left.

Well, I had to think about that one. No one has proven there is any kind of "gay gene" of course, but the interesting thing is that gay people themselves very much want it to be proven that there is one. The reason being that it proves this isn't a "choice" they make and they were "born" that way.

So I was thinking that if there is a gay gene, doesn't it follow that that gene is passed on and that my friend has a point?

Look..... I am no scientist, which is abundantly clear here, but I wondered what your thoughts are on this theory.